Digital-analog converters (DAC's) are known in the most diversified specific embodiments and are always used when digital numerical values, which are stored, for instance, in a storage component have to be converted to (quasi) analog voltages.
A fault in a DAC often leads to functional disturbances in the entire circuit. If a chip manufacturer guarantees a certain maximum fault rate, this may be maintained possibly only by using fault detection circuits or testing circuits.
Such a D-A testing circuit is shown in U.S. Pat. No. 5,583,502, in which several D-A converters are required for the test, which leads to a relatively high hardware expenditure. Also, in the circuit described there, no testing can be carried out during normal operation. Rather, test signals are applied to special test terminals in order to check the functionality of the D-A converters.
It is therefore desirable to simplify the fault detection in a D-A converter circuit and particularly to make it available online, i.e. during the running time.